The support of a H. influenzae reference laboratory for performing serological analyses and supplying vaccine is an integral component of the Meningitis Vaccine Program at the NIAID. The serologic reference laborator would serve as a focal point for the standardized measurement of anti-PRP antibody responses in children with natural disease due to H. influenzae infection, and in adults and children vaccinated with candidate H. influenzae vaccines. The project would also supply reagent grade PRP and radiolabeled PRP to other investigators for assay purposes. There is no need at this time for the contractor to provide PRP vaccine to other investigators since several vaccine manufacturers now market this product and make it available. Several laboratories are currently investigating PRP-based vaccines. The performance of antibody assays in the same laboratory using the same procedures and reagents would allow for comparisons between various patient populations and candidate vaccines.